A spokeswoman for Staffordshire police said there were more than 50 officers working on the case.
The body of the 17-year-old was found in bushes off a footpath leading to the A5 in Kettlebrook Linear Park, Tamworth, Staffordshire just after 1100 BST on Saturday.
A spokeswoman for Staffordshire police said there were more than 50 officers working on the case.
"We're continuing our extensive house-to-house inquiries and a detailed forensic examination of the scene where Heather's body was found," she said.
A postmortem examination revealed the cause of death as asphyxia but police were not prepared to say exactly how Heather died.
It was also too early to say whether she had been the victim of a sexual assault, they added.
Staffordshire Police said a passer-by discovered the teenager's body, which was concealed but not buried or covered.
In a statement her mother Karen, father Peter and elder sister Holly said her nature was similar to that of the late Princess Diana.
"She was very caring and considerate. She was always a happy and smiling girl who without reservation put others before herself.
"Her whole life was dancing. She absolutely lived for it.
"It was all she wanted to do since she was a little girl," the statement read.
Father's search
The alarm was raised on Friday night when Heather failed to meet a girlfriend outside a local dance centre between 2030 BST and 2045 BST on Friday.
When she did not arrive, her friend contacted the teenager's father.
He searched the area but found nothing and contacted police, who later combed
the area. Her body was not discovered until the following morning by a passer-by.
Lifelong friend Darren Byrne said: "We grew up together from when we were five or six years old, so you can imagine I'm devastated.
"She was a really kind girl, she would never hurt a soul."
Number of muggings
Neighbours on the housing estate where the Tell family live said there had been a number of muggings in lanes locally in recent months.
One 28-year-old mother, who would not be named, said: "My childminder was mugged a few weeks ago and an old woman was also attacked."
Detective Superintendent John Moss said: "Over the last few nights, a lot of
young people have congregated in Kettlebrook Linear Park holding impromptu
celebrations following the GCSE results.
"We are appealing to these people who may have seen Heather over the last few days."
The petite youngster, who had long straight blonde hair, was wearing black trousers, a pink sleeveless T-shirt, blue denim jacket and blue trainers on the night she disappeared.
Detective Chief Inspector Peter Hall, is expected to give more details about the investigation at a news conference on Tuesday.
Anyone with any information should call the Stafford Police incident room on 01785 234610.